A protein which binds 6-substituted adenines (cytokinins) with relatively high affinity has been isolated and purified from the 80 s ribosomes of higher plants. An antibody prepared against this protein will be checked for its effect on the spectrum of proteins synthesized in vitro in a wheat germ system translating a message from developing barley seeds. The biological role of this hormone binding protein, its distribution and turnover during the life cycle of the organism will be studied.